Improvement in Staphylococcus and Bacillus strain differentiation by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry profiling by using microwave‐assisted enzymatic digestion. (23rd July 2014)

• Record Type: Journal Article
• Authors: Balážová, Tereza; Šedo, Ondrej; Štefanić, Polonca; Mandić‐Mulec, Ines; Vos, Michiel; Zdráhal, Zbyněk
• Is Part Of: Rapid communications in mass spectrometry. Volume 28:Number 17(2014)
• Page Start: 1855
• Page End: 1861
• Publication Date: 2014-07-23
• Subjects: Mass spectrometry -- Periodicals; 543.65
• DOI: 10.1002/rcm.6966
• Languages: English
• ISSNs: 0951-4198

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="rcm6966-sec-0001" sec-type="section"> <title>RATIONALE</title> <p>Distinguishing between individual bacterial strains below the species level is a challenge to matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) bacterial profiling. We propose a quick method for improving strain differentiation of two <italic>Staphylococcus</italic> and one <italic>Bacillus</italic> species.</p> </sec> <sec id="rcm6966-sec-0002" sec-type="section"> <title>METHODS</title> <p>An alternative procedure to the extraction protocol recommended by Bruker Daltonics was developed. Ethanol‐sterilized cells of six <italic>S. aureus</italic> and six <italic>S. haemolyticus</italic> strains were digested by trypsin using 2‐min microwave irradiation and were then analyzed. Twenty‐eight strains belonging to two ecotypes of <italic>B. subtilis</italic> were subjected to the same procedure to extend the scope of the method.</p> </sec> <sec id="rcm6966-sec-0003" sec-type="section"> <title>RESULTS</title> <p> <italic>S. aureus</italic> and <italic>S. haemolyticus</italic> strains, only partially distinguishable by the standard sample preparation procedure, were subjected to microwave‐assisted tryptic digestion. The repeatability of the procedure was checked in three experiments accomplished at weekly intervals. Clear distinction of the strains was achieved by cluster analysis. The differentiation of <italic>B. subtilis</italic> ecotypes was also improved significantly by the digestion method. The discriminatory power of the novel method was supported by an increase in the number of strain‐specific peaks, as compared to the standard method.</p> </sec> <sec id="rcm6966-sec-0004" sec-type="section"> <title>CONCLUSIONS</title> <p>The method modulates the discriminatory power of MALDI‐TOF MS profiling. The differentiation of a set of <italic>S. aureus</italic>, <italic>S. haemolyticus</italic> and <italic>B. subtilis</italic> strains was improved significantly after microwave‐accelerated tryptic digestion of the cellular material. Copyright © 2014 John Wiley & Sons, Ltd.</p> </sec> </abstract>